Door latches



March 3, 1970 M. J. JAMES DOOR LATCHES Filed March 13, 1967 3 Sheets-Sheet 1 IEP-i l N V E N To R /W/c/mf; Jaarw/wis ATTORNEYS M. J. JAMES DOOR LATCHES March 3, 1970 3 Sheets-Sheet 2 Filed March 13, 1967 F/G. l

INVENTOR ///c/Mf-L Jasfffs/Jwf:

March 3, 1970 l M. J. JAMES f 3.498.660

. DOOR LATCHES Filed March 13, 1967 .Y 3 Sheets-Sheet 3 F/G. 8. 7i-

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w21/*7 *JWM ATTORNEYS United States Patent() 3,498,660 DOOR LATCHES Michael Joseph James, Charlton Kings, England, assignor to Micro and Precision Mouldings (Cheltenham), Limited, Cheltenham, England Filed Mar. 13, 1967, Ser. No. 622,750 Claims priority, application Great Britain, Mar. 14, 1966, 11,000/ 66 Int. Cl. Ec J/12 U.S. Cl. 292-173 7 Claims ABSTRACT OF THE DISCLGSURE A door latch of the mortice type has a slidable slam bolt mounted in a housing of generally tubular form. A rotary actuating member for coupling to a door handle is disposed within the housing, as is an intermediate follower member which pivots within the housing about an axis parallel to the rotary axis of the actuating member. The following member is engaged and turned by the actuating member to release the latch, with the follower member in turn engaging the bolt to produce axial withdrawal of the latter into the housing. The arrangement is such that the angular movement of the follower member is greater than that of the actuating member.

This invention relates to door latches of the mortice type having a slidable slam bolt mounted in a housing of generally tubular form, in use the latch being released by withdrawal of the bolt into the housing by turning door handles respectively mounted on opposite sides of the door and interconnected by an operating shaft. A door latch of this type is hereinafter referred to as a tubular mortice latch.

With a tubular mortice latch release is effected by a rotary actuating member which is turned by the operating shaft and acts to withdraw the bolt into the latch housing, the actuating member commonly acting directly on the bolt. The operative movement of the actuating member is limited by the lateral dimensions of the tubular housing, and as a result the maximum obtainable bolt withdrawal is limited.

The main object of the invention is to provide a mortice latch which can be designed to provide a relatively large bolt withdrawal for a given angular movement of the actuating member.

According to the invention a tubular mortice latch has a rotary actuating member for coupling to a door handle and an intermediate follower member which pivots within the housing about an axis parallel to the rotary axis of the actuating member by which the follower member is engaged and turned to release the latch, the follower member in turn engaging the bolt to produce axial withdrawal of the latter into the housing and the arrangement being such that the angular movement of the follower member is greater than that of the actuating member.

The follower member engages and pivots on a fixed abutment in the housing, this engagement defining an effective pivot axis offset vertically with respect to the bolt axis. The follower member is double-acting so that either direction of handle movement will in use effect latch release, and to this end the abutment may have a generally rectangular recess with radiused corners disposed symmetrically above and below the bolt axis and in either of which the follower member, which is received within the recess, can engage and pivot dependent on the direction in which it isr turned by the actuating member. The housing may be formed with two such abutment recesses disposed one on either side of the housing and within which are received projecting side limbs "ice of the follower member. The latter may engage in each recess to define the resting position of the bolt, the follower member being returned to the resting position by the bolt under the influence of the latch spring.

To accommodate the relative movement of the actuat- Y ingnand follower members within the housing these members conveniently have a peg and slot connection, and the actuating member preferably has a peg-like section which engages a slot, formed in the follower member, which is aligned with the bolt axis in the resting position. The peg may extend across the full width of the follower member for engagement with slots formed in inward projections of both side limbs of the follower member.

The strength of spring which can be used with a mortice latch is limited, because although it must be strong enough to provide an adequate bolt return force it must not be so strong that door slamming becomes difficult or unduly noisy. As a result the return force applied to the actuating member from the latch spring is limited although the present invention provides a marked improvement in this respect. The increased angular movement of the follower member with respect to the actuating member provides, for a given strength of latch spring, a greater spring return force acting on the actuating member. In spite of this it may be necessary to provide an additional return force if unsprung door furniture is to be used, and to this end an auxiliary return spring mayV be mounted at the inner end of the housing so that it is compressed as the actuating member is turned from the central resting position to which it is returned by the auxiliary spring. The latter may act directly on an axially slidable plunger with a concave recess engaged by an inwardly projecting lobe on the actuating member.

The actuating member may be formed with side faces which can engage the housing to limit handle movement. This enables the construction to have adequate strength for handle stops in the door furniture to be dispensed with, and the side faces may be formed on said inwardly projecting lobe.

The bolt and follower member may be formed so that they interengage, if the bolt is pushed home into the housing, to retain the bolt in a retracted and non-projecting position from which it is released on normal operative movement of the follower member. This enables a door manufacturer to supply doors with latches fitted and the bolts retracted out of the way of accidential damage during transport and fitting of the doors.

All the parts of the latch, with the exception of the latch spring, may advantageously be moulded from synthetic plastic material. A particularly advantageous construction results if the bolt is moulded from a material commonly known by the trade name Delrn with the housing and remaining parts moulded in nylon. Delrn sliding on nylon provides extremelyV satisfactorily friction characteristics.

The invention will now be further described with reference to the accompanying drawings which illustrate, by way of example, a tubular mortice latch in accordance with the invention. In the drawings:

FIGURE 1 is an outer end view of the latch,

FIGURE 2 is an axial cross-sectional view on the linev II-II in FIGURE 1,

FIGURE 3 is an axial cross-sectional view on the line III-III in FIGURE 2,

FIGURE 4 is a lateral cross-sectional view on the line 1V-IV in FIGURE 2,

FIGURE 5 is a lateral cross-sectional view on the line V-V in FIGURE 3,

FIGURE 6 is a scrap sectional view on the line VI*-VI in FIGURE 3, showing the latch in the released condition,

FIGURES 7 and 8 are detail sectional views corresponding to the section of FIGURE 3, and

FIGURE 9 is a further detail sectional view corresponding to the section of FIGURE 2.

A moulded nylon tubular housing 1 comprises a main portion 2 formed at the outer end with a fixing flange 3 and a guide bore 4 from which a slidably mounted slam bolt 5 projects. A closed-ended inner end portion 6 of the housing 1 fits closely into the inner end of the main portion 2 and is retained therein by opposed side projections 7 which on assembly click into locating recesses 8 in the side wall of the main portion 2.

The portion 2 is of truncated circular cross section, as shown clearly in FIGURE 5, having parallel side walls 9 which are disposed vertically when fitted and are joined by arcuate upper and lower walls 10. Longitudinal strengthening webs 12 moulded externally on the side walls 9 lie within the overall pitch circle of the arcuate walls 10. Thus the housing 1 iits snugly into a plain cylindrical bore drilled from the edge of a door.

The housing portion 2 is moulded with internal side abutments 13 which are joined by a central domed spring abutment 14 so as to leave clearance with respect to the arcuate housing walls 10, see particularly FIGURES 3 -and 5. The bolt 5 is moulded from Delrin with a solid outer end portion 15 providing the usual bevelled and Iradiused nose of the bolt, and an adjoining short hollow box section 16 beyond which the bolt is split to provide upper and lower inwardly projecting limbs 17. The limbs 17 pass above and below, and project inwardly beyond, the abutments 13. A latch return spring 18 is held in compression between the spring abutment 14 and the solid end portion 15 of the bolt.

A moulded nylon actuating member 19 has a square section through aperture 20 for reception o'f an operating shaft (not shown) which passes through clearance holes 22 in the sides of the housing portion 2. The actuating member 19 is journalled in the housing 1, the journals being only in part moulded at 23 in the main portion, see particularly FIGURE 9, thus enabling the actuating member to be fitted from the inner end of the housing. The journals are completed by moulded arcuate recesses at 24 in the end portion 6.

A follower member 25, which in the operative sense interconnects the bolt 5 and actuating member 19, has an outwardly projecting central web 26 positioned with side clearance between the housing abutments 13. The member 25 also has projecting side limbs 27 (FIGURE 3) which engage locating recesses 28 formed in the abutments 13, see particularly FIGURES 8 and 9. The follower web 26 has upper and lower projecting ears 29 (FIGURE 2) which enter longitudinal slots 30 in the upper and lower bolt limbs 17 and engage the inner ends 32 of these slots, so that pivotal movement in either direction of the follower member 25 within the abutment recesses 28 vwill result in withdrawal of the bolt 5 into the housing 1 to release the latch. The released condition with the bolt 5 fully withdrawn is shown in FIGURE 6.

Each abutment recess 28 is of rectangular profile with radiused corners 33 (see FIGURE 9) disposed respectively above and below the bolt axis, and the follower side limbs 27 have end portions of rectangular cross Section and radiused upper and lower ends 34, as shown more particularly in FIGURE 6, which fit closely within the recesses 28. Thus each radiused end 34 can engage and turn in the adjacent radiused corner 33 of the corresponding recess 28, in which it is received in order to define a pivot axis for the follower member 25 which axis is parallel to, and may be either above or below, the rotational axis of the actuating member 19.

The follower side limbs 27 have inward projections 35 formed with elongated and and inwardly open slots 36 aligned with the bolt axis in the resting position, as shown in FIGURE 2. The actuating member 19 has three spaced outwardly projecting arms 37 joined across at the outer ends by an integral peg 38 of circular section. The peg 38 enters the slots 36 in the follower side limbs 27,

which limbs fit between the outwardly projecting arms 37 of the actuating member 19, to provide a peg and slot connection between the actuating member and the follower member. Thus when the actuating member 19 is turned .by means of the nonillustrated operating shaft it turns the follower member 25 which in turn acts to withdraw the bolt, as shown in FIGURE 6.

As can be seen from FIGURE 6, the angular movement of the follower member 25 is considerably greater than the angular movement of the actuating member 19. The actual angular movement ratio and the resultant bolt withdrawal for a given actuating member movement depends upon the dimensions of the various parts, as will be appreciated from the foregoing description. As in the present embodiment, it is possible to achieve a very satisfactory bolt movement with a maximum actuating member movement of only 20 producing an angular movement of the follower member of about 50. This gives an idea of the advantageous movement ratios which can be achieved by means of the invention and without cutting away the housing wall to provide clearance for movement of the parts. In fact, a housing is obtained without any open side apertures other than side apertures for the handle shaft, which is extremely advantageous as open apertures allow the entry of wood shavings and sawdust which are almost inevitably present during tting.

The inner end 39 of the bolt limbs 17 are considerably narrowed and extended at one side of the bolt axis, as shown in FIGURE 7, and the ends of these extensions have radially inwardly opposing bulbous formations 40. These extensions are received in upper and lower slots 42 in the actuating member 19 which extend into the shaft receiving aperture 20, so that the bulbous ends 40 (as shown in FIGURE 3) enter the aperture 20 and engage the shaft resiliently when the latter is fitted. This resilient engagement provides some assistance in centering the handle shaft to define the handle resting position. The resting position of the bolt 5 is defined by engagement of the adjacent side faces on the rectangular projecting ends of the follower side limbs 27 with the bottom faces of the abutment recesses 28.

When the latch is to be used with unsprung door furniture auxiliary concentric return springs 43 acting on the actuating member 19 are fitted in the end housing portion 6. The springs 43 are compressed between the end wall of that portion and a plunger 44 axially slidable within the latter. The plunger 44 has a concave recess 45 which faces towards the actuating member 19 and is engaged by an inwardly projecting lobe 46 on that member. The recess 45 and lobe 46 are so shaped that movement of the actuating member 19 from the resting central position further compresses the auxiliary springs 43. Operative movement of the actuating member 19 is limited by engagement of one or other of the upper and lower side faces of the lobe 46 with the wall of the inner end housing portion 6 over a region where that portion is received within the main portion 2, as shown in FIGURE 6.

The plunger 44 is guided at the outer end by a bore 47 in the end portion 6, and at the inner end by engagement of a centrally projecting stub 48 which slides in a guide bore 49 in the end portion 6. If sprung door furniture is used, with handle return springs of adequate strength to return the handles and the actuating member 19, the springs 43 and the plunger 44 can be omitted. In this case the end portion 6 merely acts to seal the inner end of the housing 1 after the internal latch elements, other than the bolt, have been fitted through that end.

The bolt limbs 17 and the follower member 25 are formed so that they interengage, if the bolt 5 is pushed fully home into the housing 1, to retain the bolt in a completely retracted and nonprojecting position. To this end the bolt limbs 17 are moulded with tooth-like projections such as 50, see particularly FIGURES 3 and 7,

within the slots 30, and the central follower web 26 is moulded rwith corresponding recesses such as 52 for engagement by the projections 50 if the bolt is pushed fully home with the follower member 25 in the central resting position. Two projections 50 are respectively moulded on one side of one of the slots 30 and on the opposite side of the other slot 30, the recesses 52 in the follower member 25 being correspondingly positioned.

It is thus possible for a door manufacturer to supply doors with latches fitted and the bolts fully retracted so that they are not liable to accidental damage during transport and fitting of the doors. In addition a dust cap can be fitted in the open outer end of the housing, this providing a dust seal and further protecting the latch. With such a dust cap in position the door can also be painted 'without danger of the paint entering and gumming up the latch.

The projection of the bulbous ends 40 of the bolt extensions 39 into the shaft-receiving aperture 20 can be utilised in a locking arrangement employing a shaft which, in known manner, is axially displaceable from one side of the door to a locking position in which it iS inoperative to eiect latch release. Such a shaft when in the locking position, in one known construction, allows the opposite side door handle to turn freely without turning the shaft, and the shaft may be formed with a side notch which in the locking position is engaged by the ends 40. Such engagement then acts to retain the shaft in the locking position until freed by inward movement of the bolt when the limb extensions 39 clear the notch in the shaft.

I claim:

1. A tubular mortice latch comprising a housing, a bolt slidably mounted in the housing, a rotary actuating member arranged within the housing for coupling to a door handle, and an intermediate follower member also arranged within the housing so as to be engaged and turned =by the actuating member to release the latch, the follower member in turn engaging the bolt to produce axial withdrawal of the latter into the housing and a fixed abutment Iwithin the housing having Ia generally rectangular recess with radiused corners disposed symmetrically above and below the bolt axis and in either of which the follower member, which is received within the recess, can engage and pivot dependent on the direction in which it is turned by the actuating member so that in use either direction of handle movement will effect latch release with the follower member turning about a pivot axis which is parallel to the rotary axis of the actuating member and offset 'with respect to the longitudinal axis of the bolt, the angular movement of the follower member being greater than that of the actuating member.

2. A tubular mortice latch having a housing, a bolt slidable in the housing, a rotary actuating member for coupling to a door handle and an intermediate follower member which engages and pivots on two ixed abutments in the housing, such engagement defining an effective pivot axis offset vertically with respect to the bolt axis and parallel to the rotary axis of the actuating member by which the follower member is engaged and turned to release the latch, the follower member in turn engaging the bolt to produce axial withdrawal of the latter into the housing and the arrangement being such that'the angular movement of the follower member is greater than that of the actuating member, said xed abutments being disposed one on either side of the housing and respectively engaged by projecting side limbs of the follower member.

3. A latch according to claim 2, wherein the follower member has a projecting central web which passes with clearance between the fixed abutments and engages side limbs on the bolt, outwardly of the abutments, to elfect latch release.

4. A latch according to claim 3, wherein said central web has upwardly and downwardly projecting ears which respectively engage longitudinal slots in the bolt limbs.

5. A latch according to claim 3, wherein the bolt limbs respectively extend, and during bolt withdrawal slide, above and below the fixed abutments.

6. A latch according to claim 2, wherein said side limbs of the follower member engage the fixed abutments to define a resting position of the bolt, the follower member being returned to that position by the :bolt under the influence of a latch spring acting on the ibolt.

7. A latch according to claim 1, wherein the actuating and follower members have a peg and slot connection one with the other to accommodate relative movement of these two members within the housing.

References Cited UNITED STATES PATENTS 262,219 8/ 1882 Gerard 292-165 941,327 11/ 1909 Manning 292-165 2,391,736 12/ 1945 Oxhandler 292-169 2,668,072 2/1954 Falk 292-165 MARVIN A. CHAMPION, Primary Examiner R. L. WOLFE, Assistant Examiner 

